Author: Miyazaki, A.
Paper Title Page
TUXAA02 HIE Isolde Cavity Production & Cryomodule Commissioning, Lessons Learned 338
 
  • W. Venturini Delsolaro, K. Artoos, O. Brunner, O. Capatina, K.M. Dr. Schirm, Y. Kadi, Y. Leclercq, A. Miyazaki, E. Montesinos, V. Parma, G.J. Rosaz, A. Sublet, S. Teixeira Lopez, M. Therasse, L.R. Williams
    CERN, Geneva, Switzerland
  
  The lessons learned during the HIE Isolde Cavity Production, the Cryo Module Assembly and Commissioning will be presented  
slides icon Slides TUXAA02 [8.191 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-TUXAA02  
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WEXA06
 The role of cool down dynamics on the performance on Nb/Cu cavities– HIE-ISOLDE resonator as an example  
 
  • A. Miyazaki
    CERN, Geneva, Switzerland
  
  The High intensity and Energy upgrade of the ISOLDE facility (HIE-ISOLDE) is operated by superconducting quarter-wave resonators (QWR) made of a thin Nb film sputtered on a Cu substrate (Nb/Cu).The intrinsic quality factor of these cavities strongly depend on the thermal gradient (less than 1K) between top and bottom of the cavity as pointed out by P. Zhang in SRF15. Although the best cavity performance can be achieved by careful cool down, the physics of this phenomenon is not fully understood. In this study, possible hypotheses and experimental efforts are presented. A similar phenomenon has been reported on the elliptical bulk Nb cavities, and its physics was interpreted as flux expulsion efficiency. Since Nb/Cu QWR is insensitive to the flux expulsion, the thermoelectrically induced magnetic field due to Nb/Cu bi-metal structure is supposed to be the most promising hypothesis instead. Some of the model calculations and experiments to measure such a thermoelectric effect are explained. Recent findings showed that thermal gradient does not only affect the residual resistance but also temperature-dependent resistance. A result on a seamless QWR without welding will be also shown.  
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WEYA03 A Seamless Quarter-wave Resonator for HIE-ISOLDE 686
 
  • S. Teixeira Lopez, M.A. Fraser, M. Garlaschè, T. Mikkola, A. Miyazaki, A. Sublet, W. Venturini Delsolaro
    CERN, Geneva, Switzerland
  
  The superconducting linac booster for the HIE ISOLDE project, in operation at CERN, is based on NB/Cu coated Quarter Wave Resonators. The performance of the series cavities has been limited by defects in the copper substrates close to the EB weld. A novel cavity design has been developed and prototyped, in order to make it possible manufacturing of the resonators by machining them from the bulk, without any weld. The RF design was optimized for the customary figures of merit, and fully integrated in the HIE ISOLDE cryomodule. Mechanical tolerances were assessed in relation to the available range of pre tuning, and demonstrated on a dummy prototype. Beam dynamics simulations were carried out to check the effects on the beams when the new cavities will be installed in the high energy end of the linac. The presentation will cover the design and the first experimental results of the first Nb/Cu seamless QWR for HIE ISOLDE.  
slides icon Slides WEYA03 [5.262 MB]  
DOI • reference for this paper ※ https://doi.org/10.18429/JACoW-SRF2017-WEYA03  
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